Constant or variable-speed drive



Sept. 6, 1949 J. H. EGY

CONSTANT OR VARIABLE SPEED DRIVE s shees-sheet 1 Filed April lO, l946 Sept. 6, 1949. J. H. EGYv CONSTANT OR VARIABLE SPEED DRIVE 5 Sheets-Sheet 2 Filed April lO, 1946 Sept. 6, 1949. J. H. EGY

CONSTANT OR VARIABLE` SPEED DRIVl-1 INVENTOR.

3 sheets-sheet :s

fw 6 m, M W d Mm im Filed April lO, 1946 Patented Sept. 6, 1949 UNITED STATES PATE-NT- @Felge (Granted under the act of March 3, 71883? asv amended April 30, 1928; S70-0. G, 757)- 14 Claims.

The invention describedherein may be manufactured and used by or for the Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to geared power transmitting drives, particularly to a drive wherein a variable speed input produces a constant speed output andvice LVerSa, or where both input and output may be independently varied.

An object of the invention is to provide a drive wherein the power is transmitted wholly by gearing, but so arrangedzas to change ratio gradually from one ratio tov another ratio.

Another Objectis to provide a variable ratio gear mechanism wherein gear connection between the driving and the driven member is made through one of azseries of gear trains which are of different-ratios, but so arranged that driving connection may be completedthrough a gear train of a secondratio before driving connection is broken through argear train of the rst ratio.

Another object is to provide a gear drive mechanism wherein there i's a control motor, and means to cause the driven memberfto maintain a given speed ratio with respect to the control motor while the driving member may vary from a given speed to several times th'egiven speed.

Another object is to provide a mechanism which includes a plurality of gear sets, each of a lower ratio than the next, and eachcapable of being` changed by infinitesimal Iincrement from its normal ratio to the normal ratio of the next higher gear set.

Another object is to lprovide an infinitely Variable ratio changing gear mechanism having an input andan output member, one of which is constant and the other variable overa preselected speed range, the mechanism comprising several gear sets each of which transmits the power over a given part-of the requiredspeed range-` Another object is to provide a gear mechanism which includes an input member, an output member, and a control motor, wherein the input member may vary overa-wide range of speeds while the output member speed remains a function of the control motor speed irrespective of the speed of the input member.

Other objects and meritorious features will be apparent upon consideration of the following description taken in conjunction with the drawings wherein:

Fig. 1 is amore or less schematic representation of an embodiment'vof the invention in longitudinalaXial-section, the' section being taken on the line l-l offEgs. Zithroughe..

Figs. 2, 3,V 4, Iand '5 are transverse sections through the gearing taken respectively at 2 2, 3-3; lle-, andYE-Y-SDfiFig, 1.k

Fig. 6V is a fragmentary section throughjone of the worm wheelsshowing ,its vcooling means.

Like reference characters refer to like parts throughout the several jviews.

Referring now to ,the drawings, a housingqi at one end carriespa bearing l2 for the input member I4 andat'theother end. a bearing I6 for the outputvmemb'er. la.: Bearings I9 `maintain rotary concentricity,betlllleenv the inputV member lil vand the output member IKS; The output meme ber i8 carries an1 integraljsun pinion 20g-and an integral sun geal'ZZ The input member IlicarriesV oneset of integral" planet shafts 2li*v and another set ofintegralplanet shafts 256.

Planet gearszlarfe freely rotatable on the planet shafts 2.4, andplanet p inions 30,'are freely rotatable on the planetshafts .25. An internally toothed ring gear 2 lencirc1es the planet gears 2E! andlis in mesh-therewith. v An internally toothed ring gear 34rencircl'es.theplanetpinions 30'and is in mesh therewitlfi.vv Y

The planetary gear set which includes the sun pinion 20,V planet-nshaftsl, planet gears 28, and ring gear32may collectively be designatedby the numeral 3,3,.andmay be referredtoasthe low speed gear set,y while ,theplanetarygear set which includesfthersun gear,2.2, planet shafts 2t, planet pinions, 350,1and ringgear 3l-rmayAV collec'- tively be designatedbythe -numeral andmay be referred to as-.the high-speedgearlset.

In the` embodimenty of the. invention herein shown for. purposes .of `illustration,,the sun pinion 2S, of thelow-speed gfearlslfet has'. twentyteeth .and the ringgear sanas. 13,0; teeth, while the. sun gear 220i the-high-speed gear .s ,eth'as forty teeth and thering gear 3A ,has eghtyeteeth. When the ring geary ofvone. ofy thelsets, is.held nonr'otative, the driver-to-driven 4ration-will `be l.rev. ofdriver=R+Srevsof driven i. e., `one;-turnzofrthe.A drivingK4 member I 4 will :cause l1/2 turns ofithedrivenlmembergl; and when ,the ring gearof thefhighi-speed gear setzisgheldnon.-V

. aesdeei i. e., one turn of the driving member I4 will cause three turns of the driven member I8.

The output member I8 is slidable axially in the inner race of the bearing I6, and the sun pinion and sun gear 22 on the output member are so spaced with respect to the planet gears 28 and planet pinions 36 that, when one sun gear or pinion is Withdrawn axially until it is wholly out of mesh with its planet gears, the other sun gear or pinion Will be wholly in mesh with its planet gears and vice versa.

An electromagnet 36 is adapted, when energized, to shift the output member I8 with its pinion 20 and gear 22 to the right, whereby the sun pinion 20 is meshed with the planet gears 28 for low-speed ratio and the sun gear 22 is withdrawn from the planet pinions as shown (see Fig. 1).

A centrifugal governor 38 is driven by a gear 40 which is fixed on the input member I4 and is in mesh with a gear 42 on the governor. When the mechanism is at rest or at low-speed, the governor engages a governor contact member 44 with a coil contact member 46 and a terminal contact member 4B, thereby completing an electric circuit to a terminal 49 which is provided for connection to a power source, thus holding the sun pinion 20 of the low-speed planetary gear set in mesh with its planet gears 28 as shown for maintaining the low-speed ratio. A relatively heavy coil spring 50 acts through a thrust bearing 52 to shift the output member I8, thereby to engage the highspeed sun gear 22 with'its planet gears 36 whenever the governor weights 29 move out far enough to separate the contact member 44 from the contact members 46 and 48 and thereby de-energize the electromagnet 36. For purposes of illustration only, the governor may be arranged to break the electricI circuit through the electromagnet at 2,000 R. P. M. of the driving member I4.

Surrounding and integral with the internally toothed ring gear 32 of the low-speed gear set is an externally toothed worm wheel 54 with which a worm 56 is permanently meshed. Worm 56 is supported in bearings 58 carried by the housing I0 and is hollow, whereby a cooling medium may be pumped or otherwise forced through the bearings and the worm. The interior of the hollow worm may be uted as at 60 or it may be threaded, splined, or otherwise roughened to retard passage of the coolant for a purpose which will hereinafter be more fully understood when the operation of the invention is explained. A disc 50 on the rear Ibearing 58 and a like disc 6| on the Worm 56 (see Fig. 6) are held in frictional engagement, one with the other, by the reaction of the ring gear 32 through the worm wheel 54 and Worm 56 when the low-speed planetary gear serl is operating. In the embodiment of the invention herein shown, the worm wheel 54 lhas 130 teeth and the worm 56 is double-threaded, thereby providing a wheel-to-worm ratio of 65 to 1.

Surrounding and integral with the internally toothed ring gear 34 of the high-speed gear se't is an externally toothed worm wheel "62 with which a worm 64 is permanently meshed. Worm 64 is supported in bearings 66 and is hollow and internally roughened to retard passage of a coolant, hereinafter more fully explained. Discs 59 and 6| are provided as and for the purpose above explained relative to Fig. 6. The Worm wheel 62 has 96 teeth and the worm is double-threaded, thereby providing a wheel-to-worm ratio of 48 to 1.

Carried on the input member I4 is a sun gear 63 which is of wide enough face to engage two `planet pinions 'I0 and l2. Planet pinions 'I0 and 'I2 are rotatable on planetshafts 'I3 and I5 which extend laterally from the sides of planet rings 14 and I6 respectively. Rings 'I4 and 16 are rotata- |ble on bearingsV "I8 carried on the input member I4 and both have external gear teeth lwhereby they serve both as gears and as carriers for revolving the planet gears 'I0 and 12. Planet carrier ring I4 has 80 teeth land .planet carrier ring 'I6 has 90 teeth. Ring gears 80 and 82, having both internal and external teeth, surround planet pinions 'I0 and l2, respectively, the internal teeth being in mesh with the teeth of the planet pinions. Ring gear has 80 internal and 120 external teeth while ring -gear 82 has 80 internal and 180 external teeth.

A small high-speed control motor 84, which may also be referred to as a reference motor, is supported on the housing I0 and carries a 15- ltoothed pinion 8,6 on the outer end of its rotor shaft. An integral gear and pinion 88 and 00 having 75 and 20 teeth respectively, rotate on the stud S2 and drivably lconnect the control motor pinion 86 to the external teeth of the ring gear 80. A second control motor pinion 04 also having 15 teeth is connected to the external teeth or" the ring gear 82 through an idler 83. The control motor 84 should be variable in speed, but capable of remaining constant at any speed to which it is set. For purposes of illustration only, the control motor 84 may in the instant embodiment of the invention be assumed to have been set to rotate anticlockwise and 4have a constant speed of 12,000 R. P. M., whereby, with the gearing shown, the ring gear 80 will have a constant speed of 400 R. P. M. and ring gear 82, a constant speed of 1000 R. P. M., both anticlockwise and both irrespective of the speed of the input member I4.

A bracket depends from the top `of the housing I0 for supporting -a train of gears lwhich connect the planet carrying gear 'I4 to the worm 56 of the low-speed gear set. This train comprises a pinion 02 with eight teeth, gear 94 with 40 teeth, pinion 66 with 8 teeth, gear 98 with 45 teeth, pinion |00 with 10 teeth, bevel gear |02 :with 40 teeth, and bevel gear |04 also Ihaving 40 teeth. This train, together with the carrier gear 14, pinions 'I0 and ring 80 may be called the lowspeed control gearing and may collectively be designated by the numeral |01.

Pinion 92 and gear 94 are joined to rotate as one on the stud |06. Pinion 06 and gear 08 are both fast on and rotatable with the shaft |08 which .has bearing in the bracket 95. Pinion |00 and bevel gear |02 are joined to rotate as one on the stud ||0 which is xed in the bracket 85. The bevel gear |04 may be secured to or be integral with the worm 56. The ratio of planet pinion carrier gear '|4 to worm wheel 54 is 1 to 3%3.

Another bracket |05 depends from the top of the housing I0 for supporting .a train of gears which connect the planet carrying gear 16 to the worm 64 of the high-speed gear set. This train comprises a .pinion I|2 having 10 teeth, a gear I|4 having 40 teeth, pinion |I6 having 10 teeth, gear IIS having 60 teeth, pinion |20 having 10 teeth, bevel gear |22 having 40 teeth, and bevel gear I 24 also having 40 teeth. This train, to

,Pinion i l2 and gear H4 .are joinedto rotate .Y as oney on the stud [2.6. Pinin'gl L6 andfgear H8 are rothv rast l(mand'roliaif-.atie Wahrheiten 12a which has bearing inthe bracket 1,05. Pinion |20 and bevelgear |22 are j oinec'iftortatelas one on.

Operation Leiit .De assumed fier geringes f illustration that the exemplie'ation of the invention Yherein shown ,and described is ybeinglunsed` onan'aircraft; that a 50 I-I. P. Vgenerator'attachedy to the output member I8 must bevleptat a constant speed of 6000 R. P. M. at all.speedsptheinput member l; that the inputi member lfiis drivably attached to the engine of the aircraft;v that said engine may revolveas slow..as.800.R.' yP. M. when the craft is being taxied, asfast as 2700 R. P. M. vat take-.off ,and .preferably katalooht 2000 R. P. M. when cruising which is the greater portion of the time;.andithahtheismall.reference motor 84 is of quarter horsepovvercapacity and maintains an exact constant speed or" 12,000 R. P. M. The input ,memberl' and output inember i8 may, for illustrative purposes be taken to rrevolve clockwise when.iai@neri-C from, right-.12.0 lleft f with reference to ,other rotatingparts, 7they may also be assumed to `vbe viewedirornorighttoleft of Fig. l.

If the ,engine isnowuoperated athQOiuR. P. the .governor 3&Wi11 ,have-.the eletrical. .Qoptacts d6 and 48 connected through the aon-tagt, (iii, whereby the electromagnet l@i6 .will be y`energized, and the output member-i8 will be shifted to the righthand position,v i. e., thre highspeed sun gear 22 will be out of mesh .withits planet pinions 30, and the sun gear .Will be. inmehwiih its planet gears 28 as seen in Fig. l.

With the sun gear 08 being revolved at a speed of 800 R. P. M. by the input member lli, and the ring gear 80 being revolved at a'speed kof 400 R. P. by the contrplnrnotror iijgthe planet pinion 'l0 will be rh'tatingnonits Aplanet shaft i3, but will not be revolving arou'nd the axis of the sun gear-68. rlheplanet .ciarrierr therefore remains nonhotative,..wherehy thatV part of the low-speed control gearing which connects the carrier gear 'I to the Worm 5S, together with the worm and worm wheel 56 .afidll vvill-all. be nonrotative which is a eondition precedent to the low-speed.planetarygeansetg, i. e., the sun 20, planets 28 and ring 32, operating at a driverto-driven ratio of l to 71/2 as nerei'nbefore stated. As soon, howeverQas the inputwinember j' rotates thesunfgeari at anv'speedabove ,800 -R.

P. M., the planet'carrier gearidrotates'cloekwise in direct proportion to thel exessof driver-.revs. over 800 R. P. M., whleby-'fthe `ring k'gear Elfi' through that part of the control ,gearing Mii-Vl .which `onnects ittothe arrvergear "ifi, vis rotated rcloekwise, an amount `whizhreducesthe ratio of the lowspeed gear set 3:3`,A`from,1to j'l/gwdriverto-drivjen to whateverrat'io isnece-ssary to inaintain a Speed QLGQQO R- P-[Mf the..- @riempels;

., `As, an illustrative .examplephthe above ,coindition, assume that the sped mi; -ber I0 has been raised from'S 1,tfo l The ring gearilA being driven '1b th tor 80 continues .to revolveatQa 014 P. M. The ring gear 8 Elhas, ,30 in rn while the sun gear 68 hasll.l0,.,ex ter"al With the ring gearandsungear 6 bot re- Volving at different speedsandinbp k i tions, the p-lanet pinionA carrielrglear.. t volve in accordancewith the ,followingequa on 1 rev.of the sun .gearS'l 'mt-famiglie ,of the carrier gear 1,4, wherein S= number of teeth on thesun-.gear 5077.40

R=number of internal -teeth en@the-.-ringigear revs. of 510W driver 4400 revs. of fast driver-7,100.0

l substituting,

1 rev. of the sun gear-0 8:

4o ...8 0 ,1 80+@ 10.00 SOHNE-W' of the -carrier gear 74.

At 1000 R. P. M.A of the-sungear 68 the carrier gear M revolves 1000 1/15=. 6V6'2/3 VR. P. M.

Since the ratio ofl the' e'arriergar-'Fdt the slow Speed mein ring eearfis. 1 12.0. 3.5/13.;thefririaeealf?. during the 1000 fers-,0f the infant membenlevill have revolved 3%3X662/3=2301%3 revs.

With the carrier arms Menthe input 'member revolving 1000 R. P. ariel-the ,gearISZ-.r'ef volving 2301%3 R. P. M., both in he saine-(direction, the sun pinion 20 will revolve imachordanee with the following equation:

1 rev. of the carrier armsu24= JEH-S R S Xs of the sun pinion .2, wherein S=I`1umber of teeth-on. thesun pinin-20=g0 R-fnumber of teeth ,onjher'iigfkgean TBVS.

hmmfwe wrevs. of fast 1driver 1000 substituting,

i 1 rev. of the carrier .larrnsagll +20-2301%3X`130 20 of the sun pinion 20.

At 1000 R. P. M. of the carrier. arms 24, the sun pinion 20 will rotate at ,aspeedof 6000 R. P. M.

Thus far it has been shown that whether the input member rotated 800 QrlQQQRifPili/Il., thevoutput member ineithe ,uqaselrqta 000 R- P- Mw .it 39mg SSuUlediQf QQUSe/ iletQQnf trol motor 00 continued to rotate at'the constant speed of 12,000 R. P. M. tonvhilitwaset .inhQth cases. By the same procedurelin calculation, `it may be shown that no matter at whatspeedi'he input member rQtateathe/Joutphut will continue to rotate at 6000 R.`P. 'Mfas long as rthe control motor rotates 1A2,000;R. .P. 3M.

While the low-speed lgear set 3,3.,was in operation as above described, the high-speed'gearset l35 was also revolving butwithoutlgad. L ring gear zwas beingleptgab ,1. l,of 1000 R.P. M., the sungea'n w sc i rotated by the input Iiqemloer` l R. P. M. to allow theV planet pinion a 1 er to become nonrotative. At 2000 R. P. M. of the input member, therefore, the ring gear 34 of the high-speed gear set 35 and those of the control gearing which connect it to the carrier gear 16, became nonrotative, and it is at this speed that the governor 38 acts to shift the load to the highspeed gear set as hereinbefore described.

It should be understood, however, that the output member I8 may be shifted axially from one of its positions to the other at any speed of the input member, or it may be shifted to any position intermediate its two positions where both sun gears are partly engaged with their respective planets, since the relative speed of either sun gear 20 or 22 and its planets 28 or 30 is always the same at any speed and in any position to which the output member may be shifted, whereby shifting is always accomplished without gear clash.

As hereinbefore stated, the ratio of the highspeed gear set is 1 to 3 driver-to-driven revs.

when the ring gear 34 is nonrotative, which is at 2000 input revs. Since the input speed upon takeoff may be as much as 2700 R. P. M., the highspeed control gearing 125 must, at speeds over 2000 R. P. M. slip off the extra 700 revs. That it will do this may be shown by example as follows:

1 rev. of the sun gear 68:

S R+s of the carrier gear 16, wherein S:number of teeth on the sun gear 68:40. R=number of internal teeth on the ring gear X revs. of slow driverm 1000 "revs. ofi fast driver 2700 substituting,

1 rev. of the sun gear 68:

I 1000 30 l 80+40 2700 80+40-s1 revs' of carrier gear 16.

At 2700 revs. of sun gear 68, the carrier gear 14 revolves 2'100 %1=2331/3 R. P. M.

Since the ratio of the carrier gear 16 to the high speed main ring gear is 1 to 41/2, the ring gear 34, during the 2100 revs. of the input member I4, will have revolved 41/2 X233 6:1050 revs.

With the carrier arms 26 on the input member revolving 2700 R. P. M. and the ring gear 34 revolving 1050 R. P. M., both in the same direction, the sun gear 22 will revolve in accordance with the following equation:

1 rev. of carrier arms 26:

egi-

X s revs.

of sun gear 22, wherein S:number of teeth on the sun gear 22:40. R=number of teeth -on the ring gear 34:80.

revs. of slow driver 1050 revs. of fast driver-2700 substituting,

1 rev. of the carrier arms 216:

40 "700X40-239revs' of sun gear 22.

At 2700 R. P. M. of the carrier arms 26, the sun gear 22 will rotate 2700 2%:6000 R.. P. M.

The following example will serve to illustrate that a shift from the low-speed to the high-speed gear set or vice versa may be made without clash 8 or that both gear sets may be half in and half out of mesh and still operate satisfactorily.

Assume that purposely or inadvertently at 1500 R. P. M. the output member I8 is shifted to a point where the sun pinion 20 and the sun gear 22 are both half way in mesh. As before shown, at any speed of the input member, the output member will be rotating 6000 R. P. M.

Clockwise rotation of the ring gear 32 will then be determined by the following equation:

In the low-speed gear set 33, 1 rev. of fast driver s:

R g revs. of driven member R wherein C=slow driver rotating 1500 R. P. M.

S:fast driver rotating 6000 R. P. M. and having 20 teeth.

R=ring gear:driven member=130 teeth.

=revs. ol` slowmdrivern 1500 revs. of fast driver- 6000 substituting,

1 rev. of fast driver S:

mXm- E) revs. of driven member R 1 rev.of fast driver 8:752 rev. of R. 6000 revs. of S:

1 rev. of fast driver S:

=807%3 revs. of R of driven member R, wherein C, the carrier gear 14:slow driver rotating 2331/3 R. P. M.

S, the sun gear 08:fast driver rotating 1500 R. P.

M. and having 40 teeth.

R, the ring gear 80=driven member having 80 internal teeth.

revs. of slow driver 2331 X'evs. 0f fast driver-1500 substituting,

l rev. of fast driver S:

1500 so B im 1500 revs. of fast driver S:'l500 -%5:400 or 400 turns anticlockwise, which is the speed and direction of the ring gear 80 now being maintained constant by the control motor 84.

The above calculation shows that, in the lowspeed gear set, if the input member is revolved at a speed of 1500 R. P. M. and the output member in the same time also is revolved at a speed of 6000 R. P. M., the gear 80 will be revolved at a speed of 400 R. P. M. even if the motor 84 should be disconnected therefrom. The same calculation will now be applied to the high-speed gear Set. In the high-speed gear set 35,

9 l'revgof fastdriver f5# i revs.

of Vdriven'member R, wherein Clis therslow.,driverrotating 1500- R. P.v M.

`-S `-is the fast driver rotating ,6000. R.v P. M.

R=driven memberzring gear.= '80l teeth of driven memberV R, .wherein C, the carrier gear 1t= slo wr driver rotating 166% RrP. S, theY sungear Sli-:fast driver rotating 1500 R.

P. M.,= 40 teeth. R, the ring gear 82=driven member having 80 Y internal teeth.

,revs.4 ofjslow driver 166% .revs. of/ fast 'driver-` 1500 substituting,

1 rev. of Ifast drivers.:

166% so+4o 2/ Y1500 so :so- 3 1500 revs. of fast driver S=\1500 %-71000, i. e., 1000 turns '.Manticloclzwise,` whichfis the speed and direction -of. the ring jgearz'maintained 4by the control motor 84.

lrornr thefforegoing, it ,will be seen that if. the speed of the control gear 30 is held at exactly 12,000.11- P, M., the .output member IS will maintainV a confsta'nt'speed lof 6000 R. P. M. irrespectiveof the speed of the input member. .In View of thisfactit'is obvious that if itbecomes desirable tov-ary the speed of the outputr member, it can readilyfbefdone ,by merelyva'ryih'g the Speed of the@contrl,` motor 84 whereby thespeed ofthe output member will vary in r'direct proportion to the variationof the control motor speed irrespective of the's'peed of the input member.

It `isncted that the low-speed gear sett-3 is so constructedthat the main ring gear 32 and the controlgearing |01 are all nonrotative at 800 R. "P. Alv'ixbut that they increase in speed as the speed .of the input member goes up. vThe higher the Ainput member speedthe higher the speed of the controlgearing lr'mist'loe to maint/ain the' same outputgm'eniber speed.

It is for-:this reason that the range which may be covered'by a single gear set is preferably limitedfin order to hold the speed of the control gearing,Aparticularlyvthe worm 56 within reasonable bounds. :In the embodiment herein'shown, the'low-speed Ygear set Covers a rrange of ratios from a low of SOO-to-'GGO drivereto-driven Ato va high of 20,00-to-6000 driver-t'o-driven` before the governor acts to relieve the'fast rotating Worm E36 of its duty by transferring the load to the highspeed gearV set which starts withV a ratio of 2000- to-SOOO driverfto-driven at which ratio its coutrol gearing $25 is nonotative.

It is therefore obvious' that the'higher the efficiency that is demanded yof the linvention the more restricted shouldfbetherange of ratios which a single gear set should be made to cover. Where' a considerabletotal speed range is to vbe covered, more than two gear sets may preferably be used 4each with itsrattendant control gearing. By thus employinga greater number of gear sets with meansfor transferringthe load from one to the next, the worm and Wheel gearing is not overspeeded, Yand since the speed of the gearingrbeing disengaged in the transfer of the4 load is exactly equal to thespeed of the gearing being engaged, a smooth'and unnoticeable transfer is provided.

It should also be noted that the design of the worm and worm Wheel of a gear set should be such that the friction between the worm and the wheel teeth together with the-'friction Vbetween the discs' and 6l (see Fig'. 6) and such bearing friction as may exist will-make the worm just self-locking but near enough reversible that the slightest power applied bythe lcontrol motor 84 will start rotation of the worm'rand its attendant control gearing and maintain rotation at a speed always commensurate with the changing relation between the input and output speeds.

The cooling of the worms 56 and/64 is an irnportant feature of the invention. Since the speed of the worm gearing varies Yover a wide range, depending on the range of ratios which a single gear set is to cover, the coefieient cf friction will also vary, being, let ,us say, .lat the lowest speed at which the worm rotates to ,01 at the highest speed at which it rotates,thereby imposing fa variable load onl the control motor whichmay affect its synchronism.

VIn order to'counteract the effect of this variable coefcient of friction and atV the same time provide means toeifect transfer of the heat generated bytheworm gearing, theworm audits bearings Aare constructed as 'described relative to Fig. 6. The restrictiontll to the iiow of a coolant through the opening the Wormcreatesra torque which increases ,with thewrm speed. Since the torque produced by the friction 0f the `worm gearing decreases with the worm speed, the roughening or other restriction to flow within the worm is'made such as to maintain lan even balance betweenthe decreasing torque created by the mechanicalkfricticn of the worm gearing and the increasing torque created bythe iiow of a cooling fluid through the restricted passage, wherebyA the control motorandvcontrol gearing carry only a minimum uniform load.

In order to maintainnthetemperature of the cooling medium relatively ,lcwand uniform, the circuit may include any suitablelcontrollable heat transfer unit through which 4the collant leaving one end of the worin must pass before it may reenter at the other'end.' Y

it will of course be understood that while, in the embodiment 'shown,rthe speed of the Vinput is variable and that of the output is constant, the device may be adaptedlfor a constant input and variable output. Moreover7 while the device shown employs va mechanical input and ,electricalY output, either orboth` input andcutput may be hydraulic, electric or mechanical.

Furthermore, while the device shown by wal7 of an example includes two ratio changing units, either of those may be used singly if the range which they are to cover is not too great, or, when the overall ratio range is quite large, as many more ratio changing units as are required to cover the desired range may be employed.

While the device shown suggests the use of a single power input unit of variable speed, such as an aircraft engine driving a single power output unit of constant or controllable speed, such as a generator, it will be obvious that, if a series of devices, such as are herein shown, have their input members i4 thus coupled to power input units, and their output members I8 thus coupled to power output units, and synchronous control motors 84 are employed and connected in parallel to the same source of energyrsuch as the small inverter employed on aircraft, the output members i8 will not only each maintain a constant speed but all of the series will be kept at the same speed irrespective of variation in speed between one or another of the power input units.

Having thus described an embodiment of my invention, I claim:

l. A variable ratio gear mechanism which comprises two relatively rotatable members, a planetary gear set which includes a power transmitting sun gear fast on one of said members, a power transmitting planet gear on the other of said members and a power transmitting reaction gear, and planetary control gearing which includes a sun control gear fast on the said other of said members, a planet control gear drivably connected to the power transmitting reaction gear, a control reaction gear in mesh with said planet control gear and means to control said control reaction gear.

2. A planetary power transmitting gear set which includes a power transmitting sun gear, a power transmitting planet gear in mesh with said power transmitting sun gear, a power transmitting carrier for said power transmitting planet gear and a power transmitting reaction gear in mesh with said power transmitting planet gear, in combination with a planetary control gear set which includes a control sun gear, a control planet gear in mesh with said control sun gear, a control carrier for said control planet gear and a control reaction gear in mesh with said control planet gear, means drivably connecting said control carrier to said power transmitting reaction gear, and means for controlling the speed of said control reaction gear.

3. In combination, an input member, an output member, a control sun gear on the input member, a power transmitting sun gear on the output member, a control planet gear in mesh with the control sun gear, a power transmitting planet gear in mesh with the power transmitting sun gear, a control reaction gear in mesh with said control planet gear, a power transmitting reaction gear in mesh with said power transmitting planet gear, a carrier on said input member for said power transmitting planet gear, a carrier for said control planet pinion drivably connected to said power transmitting reaction gear, and means for controlling rotation of said control reaction gear.

4. The combination of an input member, an output member, a control sun gear on the input member, a power transmitting sun gear on the output member, a control planet gear in mesh with the control sun gear, a power transmitting planet gear in mesh with the power transmitting sun gear, a control reaction gear in mesh with said control planet gear, a power transmitting reaction gear having internal teeth in mesh with said power transmitting planet gear and external worm wheel teeth, a Worm rotatably supported for engagement with said worm wheel teeth, ,a carrier on said input member for said power transmitting planet gear, a carrier for said control planet pinion drivably connected to said worm, and a power operated control means for controlling the speed of said control reaction gear.

5. The structure dened in claim 4, wherein the worm is hollow and adapted for the passage of a coolant therethrough,

6. The structure dened in claim 4, wherein the worm is hollow and adapted for the passage of a coolant therethrough, and wherein the hollow of the worm is roughened in order that said passage of coolant will create a resisting torque which increases with increase in worm speed.

7. In combination, a power source, an input member drivably connected to said power source, an output member, a plurality of control sun gears on the input member, a plurality of power transmitting sun gears axially spaced on the output member, a plurality of control planet gears each in mesh with their control sun gears, a plurality of power transmitting planet gears each adapted to be engaged with their power transmitting sun gears one sun gear at a time, a plurality of control reaction gears in mesh with said control planet gears, a plurality of power transmitting reaction gears in mesh with said power transmitting planet gears, a plurality of carriers on said input member for said power transmitting planet gears, a plurality of carriers for said control planet pinions drivably connected to said power transmitting reaction gears, control means, operable by a power source which is independent of the rst power source, for rotating said control reaction gears at a selected speed, but each at a diiierent speed, and means operative at a predetermined speed to shift one of said power transmitting sun gears out of mesh with its planet gear and another of said power transmitting sun gears into mesh'with its planet gear.

8. The structure of claim '7, wherein the last said means is an electromagnet.

9. The structure defined in claim 7, wherein the last said means is an electromagnet with a speed responsive governor adapted at predetermined speeds to energize or de-energize said electromagnet.

10. In a power transmitting mechanism, two relatively rotatable members, a planetary power transmitting gear-set having an element fast on each of said members and an element serving as a power transmitting reaction element, a planetary control gear-set having a control element fast on one of said members, a second control element, power transmitting means of fixed ratio connecting the second control element to the reaction element of the power transmitting gear-set, and a third element acting as a control reaction element, a source of rotatable power apart from said members, and power transmitting means of xed ratio connecting said source of rotatable power to said control reaction element.

11. In a power transmitting mechanism, two relatively rotatable members, a three-element planetary power transmitting gear-set having one element fast on each of said members and a third element serving as a power transmitting reaction element, a three-element planetary control gear-set having a control element fast on one of said members, a second control element, a

train of toothed gearing connecting the second control element to the reaction element of the power transmitting gear-set, and the third control element acting as a control reaction element, a source of rotatable power apart -from said members, and a train of toothed gearing connect ing said source of rotatable power to said control reaction gear.

12. In a power transmitting mechanism, two relatively rotatable members, a planetary power transmitting gear-set comprising a pinion carlrier and its pinion and two gears both in mesh with said pinion, one gear being fast on one oi said members, the said pinion carrier being fast on the other of said members, and the other gear acting as a power transmitting reaction gear, a planetary control gear-set comprising a pinion carrier and its pinion, and two gears both in mesh with said pinion, one of said gears being fast on one of said members, power transmitting means of fixed ratio connecting the carrier of the con trol gear-set to the reaction gear of the power transmitting gear-set, and the other gear of the control gear-set acting as a control reaction gear, a source of rotatable power of constant speed apart from said members, and power transmitting means of fixed ratio connecting said source of rotatable power of constant speed to said control reaction gear.

13. In a power transmitting mechanism, an input member, an output member, a planetary power transmitting gear-set comprising sun and ring gears, a planet pinion and a planet pinion carrier, one of said gears being fast on said output member, the carrier being fast on the input member, the pinion being rotatable on the carrier and in mesh with both gears, and the other gear acting as a power transmitting reaction gear, a planetary control gear-set comprising control sun and ring gears, and a control planet pinion and its carrier, one of the gears being fast on the input member, toothed gearing of fixed ratio 14 connecting the control carrier to the power transmitting reaction gear, and the other gear serving as a control reaction gear, a source of constant speed rotatable power apart from said members, and power transmitting means of fixed ratio connecting said source of rotatable power to said control reaction gear.

14. In a power transmitting mechanism, an input member, an output member, a planetary power transmitting gear-set comprising sun and ring gears, a planet pinion and a planet pinion carrier, the sun gear being fast on said output member, the carrier being fast on the input member, the pinion being rotatable on the carrier and in mesh with both gears, and the ring gear acting as a power transmitting reaction gear, a planetary control gear-set vcomprising control sun and ring gears, and a control planet pinion Vand its carrier, the control sun gear being fast on the input member, toothed gearing of fixed ratio connecting the control carrier to the power transmitting reaction gear, and the ring gear of the control gear-set serving as a control reaction gear, a source of constant speed rotatable power apart `from said members, and power transmitting means of fixed ratio connecting said source of rotatable power to said control reaction gear.

JOSEPH H. EGY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 548,860 Ames Oct. 29, 1895 899,974 Harter Sept. 29, 1908 1,559,975 Y Murray Nov. 3, 1925 1,658,673 Fontaine Feb. 7,1928 2,363,201 Popoff Nov. 21, 1944 

